Because it was not for their day.
Daniel was told not until the end times.
Daniel 12:4 But thou, O Daniel, shut up the words, and seal the book,
even to the time of the end: many shall run to and fro, and knowledge shall be increased.
The disciples were told by Jesus when they questioned him about the restoration of the Kingdom of Israel.....
Acts 1:
6 When they therefore were come together, they asked of him, saying, Lord, wilt thou at this time restore again the kingdom to Israel?
7 And he said unto them,
It is not for you to know the times or the seasons, which the Father hath put in his own power.
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Even the apostles couldn't put everything together start to finish, because the understanding was sealed until the end times - our generation.
Ezekiel 39 is critical because it pinpoints when the 7 years takes place. Immediately following the destruction of Gog's army, the Muslim coalition bent on destroying Israel. Producing the illusion of peace and safety following the destruction of Gog's army.
7 years after the destruction of Gog's army is the Armageddon feast in Ezekiel 39:17-20. Equates to Revelation 19:17-18.
We are really close to Gog/Magog.